Halogenated alkoxyphthalocyanines are disclosed in EP 0373643 and Japanese Patent Application Laid-open Nos. 197280/1986 and 85630/1975.
Techniques of using the halogenated alkoxyphthalocyanines as optical recording media are described in EP 373643, Japanese Patent Application Laid-open No. 197280/1986, U.S. Pat. No. 4,298,975, EP 353394 and U.S. Pat. No. 4,769,307. However, the optical recording media using the compounds described in the above-mentioned patents are insufficient in sensitivity, a refractive index, recording properties and reflectance.
In particular, EP 373643 discloses the phthalocyanines each having four alkoxy groups, or four alkoxy groups and four substituents. However, among the phthalocyanines disclosed in this patent, for example, the compounds shown in Examples 93 to 100 had a small refractive index of 2 or less at 780 nm and insufficient sensitivity and recording properties. On the other hand, the compounds shown in Examples 100 to 103 could not provide an industrially homogeneous recording layer, because the solubility of these compounds in a coating solvent was 10 g/l which was too low to prepare the optical recording medium therefrom in accordance with a spin coating process by the use of a polycarbonate substrate. In addition, the sensitivity, recording properties and reflectance of the media were insufficient.
With regard to the halogenation of the phthalocyanine, Publication Board Report No. 65,657 describes a method in which antimony trisulfide or aluminum chloride is used as a catalyst. However, this method could not be applied to such a phthalocyanine containing the alkoxy group as in the present invention, since the alkoxy group substituted on a benzene ring, for example, a phenyl alkyl ether decomposes in the presence of aluminum chloride into phenol and an alcohol. This decomposition reaction is described in the literatures of Chem. Ber., 76B, 900 (1943), J. Org. Chem. 27, 2037 (1962) and Chem. Ber., 93, 2761 (1960).
Furthermore, J. Org. Chem., 6, 852 (1941) and Chemical Industries, 1138 (1967) describe the decomposition reaction in which an acid byproduced in the halogenation reaction, for example, hydrogen chloride or hydrogen bromide produced at the halogenation with chlorine or bromine decomposes a phenyl ether into phenol and an alcohol.